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WILLIAM. D. ANDREWS, OF NEW YORK, N. Y.

Letters Patent No. 60,662, dated January 1,1867.

IMPROVEMENT IN STEAM GENERATOR.

TO ALL WHOM IT MAY CONCERN:

Be it known that I, W. D. ANDREWS, of the city, county, and State of New York, have invented a new and useful Improvement in Steam Boilers; and I dohercby declare that the following is a full, clear, and exact description thereof, which will enable others skilled in theart to make and use the san1c,`rcfc,rcncc being had to the accompanying drawings, forming part of this specification, in which- Figure 1 is a central longitudinal vertical section of the boiler; and i Figure 2, a transverse vertical section.

Similar letters of reference indicate like parts.

The fire-space A is formed of the crown-sheet-plate B, and the side and end plates, respectively marked Cv C1 C2 C", and embraces the entire horizontal area ofthe boiler, except the narrow water-spaces, a, which entirely surround and intervene betweenit and the outer shell, b, and heads, c e2. Through the water-space at the front end of the boiler is an opening, E, for the introduction of fuel into the {ire-place, A, upon grate D, the top of which it is intended to have nearly on a level with the lower side or bottom edge of opening E. This opening is to be provided with aI double iron door, through the outer section or plate of which graduated openings are to be made and perforations through its inner section or plate for the admission, in quantities as may be desired, of atmospheric air to the lire-place without passing through the grate. Through the water-spaceat the back end of thc boiler, opposite opening F, is another opening, I, (the top or uppcr'cdge of which is as near the crown-sheet as it is practicable to form it,) for the passage of the unconsumed gases from the fire-place, A, into the combustion chamber, H. This opening is so contracted that, while giving a sutlicient'draught to the boiler, it will somewhat retard thelescape of the gases from the tire-place; thus increasing their consumption therein and imparting more of their heat to the surrounding surface. The combustion chamber, I-I, is formed by the breeching M, which is to be attached to the boiler so as to be susceptible of detachment therefrom, and in practice it is either intended to line it or make it double, with a filling of some nonlconducting material.` The combustion chamber, II, extends from below the opening I to a point above the ends of the tubes F, covering and forming a communicating passage between them of amuch larger area than the opening I, which enlargement allows and causes the gases entering it to eddy and expand therein, and thereby 'to thoroughly combine and mix with the atmospheric air admitted to said chamber through the graduated openings, N N N, in suchquantities as the various kinds of fuel may require. In the back part of chamber II, attached to the breeching M, is a plate of iron, I', of somewhat greater diameter than opening I, the objects of which are, first, to protect the portion of the b'reeching opposite saidopening from the intense heat of the gases impinging upon it direct from the ireplace; and, secondly, to form a passage for a portion of the atmospheric air entering at the openings, N N N, whereby it is made to become highly heated in said passage before lmixing with the ignited gasesJ above or in the upper portion of the chamber. This distribution of atmospheric air by openings extending over a considerable surface, with the further distribution caused by the passage behind the plate I', creates a most thorough and perfect combustion of the gases in chamber I-I and tubes F. The tubes F F extend the entire length of the boiler, through the water-space C4, above the lire-place A, passing through heads G G2, in which they are expanded and secured in the ordinary manner, thus connecting and strengthening them.. These tubes -form passages from the combustion chamber, II, to the chamber K, formed by the breeching I3, attached to the boiler so as to be susceptible of attachment or removal, and provided with an opening, L, at the top communicating with the chamber or exit flue. The backb1eeching M isprovided with a door, M2, opposite the ends of the tubes for convenience of cleaning them without det-aching the said breeching. In the bottom of the frontbreeching I3 an opening D is made, provided with a slide, I4, which serves the purpose of a damper, and also as a ready moans of discharging or removing any deposits that may collect therein from the cleaning of the tubes or otherwise. The deposits in chamber II may be discharged through the openings N, or through the opening I and grate D, into the ash-pit below the-latter. The sides and ends of the fire-place are to be connected tothe outer shell and heads of the boiler by screw-braces or socket-bolts in the usual manner. The crown-sheet B is stayed and connected to the shell b by a series of radiating braces, P l? P, and braces Q Q Q are extended across the boiler below between and above the tubes F, connecting together, staying and strengthening the straight sides of the boiler above the fire-place. Similar braces, Q2 Q2, connect together and stay the portion of the boiler-heads above the tubes F. The shell of the boiler and back head-plate are to be extended downward below the grate a. sulicient distance to leave an opening in front, of/a' proper sizefor the admission of the necessary amount of air to the grate to support combustion in the fire-place, thus forming an ash-pit, M, and insuring an equable distribution of air to all parts of the grate. The front headvis to have its-Hangcfturried outward, and all the other parts are to be put together and riveted before inserting the said head, after which the few rivets necessary tc connect the braces to it are inserted through the tube openings, and the riveting necessary to connect the said head to the shell is done entirely outside of the boiler. 'By this mode a manhole is avoided, and the riveting as well as the iitting of braces is greatly simplified and facilitated. As a proper proportion of the several parts has much to do with the proper and economical Working of a boiler of whatever construction, I Would here state that experiments in the use of different kinds of fuel in my improved boiler, such as, for instance, anthracite and bituminous coal, oak and pine Wood of various degrees of seasoning, have led me to adopt the following proportions, with which satisfactory results with cach kind of fuel above named are secured, no smoke escaping from the boiler, and the unconsumed gases leaving it at as low a' temperature as is desirable; the only and principal change necessary in usingl the diiferent kinds of fuel named above being 4to admit more air through the openings N N to chamber H ivhen burning bituminous coal or Pinewood than when using hard or anthracite coal or hard Wood7 a little experience enabling any engineer to so graduate the said openings as to secure thevproper economical result. In the construction of the boiler, the'relative proportions of its parts are about as lollovvs, viz: The height of hre-place should be about three-fifths its width; one square foot of grate surface to eight square feet of re surface, and openings in the grate to be one-half its area; one square foot in opening I to' twelve square feet of grate surface; Water line to be three inches above the top row'v of tubes; the semicircular steam space to have a height equal to one-hali` the width of the boiler; the combustion chamber, H, to have three square feet of horizontal area to ono square foot in open-- ing I I; for a three-inch tube a length of four feet, and for-tubes of less or greater diameter the ratio of length tol diameter to be the same as for a three-inch tube; the entire area of tube openings to be oneand a half time greater than opening I, and the horizontal arca of chamber K to be equal to the area of all'the tubes, and the area 0f exit-opening to be equal. to opening I; openings for admission of air to combustion chamber to have one-twelfth the aggregate area of opening F2. As it is not at all times practicable to maintain the same relative proportions of parts above specicd in boilers of different sizes, when changes are made, it is better to increase the proportionof grate surface, height of fireplace, height of steam-space, area of combustion chambcrhdiameter of tubes,r and decreasethe area of opening I and the aggregate area of tubeopenin@.

The operation of the boiler is as follows: Proper fuel is first introduced intothe hre-place, A, and ignited upon grate D, which, having a very large area, admits a great amount of air at a low velocity. The hre-place being also very large, enables the atmospheric air to more thoroughly mingle with the gases arising from the burning fuel, increasing and intensifying the combustion in the large space above the fuel, the extended surfaces of which rapidly communicatel the heat tothe surrounding Water. :The combustioniin the fire-place is still further increased by the admission of air above the grate through graduated openings in door F1 in quantities proportioned to the kind 'of'fucl used. The uneonsumed, but still consumable, gases escaping from the fireplace through the'con-tracted opening I, are in chamber II permitted to expand, and at the same time mix and combine with a fresh 'supply ofairy admitted through the openings N N N, by which means the combustion is much accelerated and becomes very thorough and complete, while passing through said'chamber and the tubes F,so that in the escape of the uuconsumed gases from the chimney no smoke is visible even When using bituminous coal, provided a proper and suiicient supply of air be admittedthrough the openings N. The escaping gases in their passage throughtubes F so ei'ectually communicate their heat to the Water surrounding them that they reach chamber K at a temperature a very little above that of the steam in the boiler, and as the great bulk of the Water is over the iire and surrounding the tubes, and the most intense heat in the tire-place is at the back portion. of the boiler and the tubes at the same end, the result is that the Water there `rises and is replaced by the colder Water from the front end-passing along the sides through the side water-spaces about the fire-place, A, thus keeping up the supply and insuring a steady and regular circulation Ain all parts of the boiler, a well-known requisite for creating steam rapidly and economically. IThe disposition of the tubes above the fire-place, and the carrying of the water above their level, obviatc the very serious danger of explosions in boilers, having the crown-sheet near the surface of thc Water and above the tube level, when, by neglect or inattention, the water is allowed'to get a very little below the ordinary height. The increased depth of the Water also insures its being kept in contact with the crown-sheet, however intense the heat in the fire-place, and the net-Work formed by the tubes and braces also eonduces to the same result by breaking the steam globules and permitting the escape of the' s team to the surface with the least possible disturbance of the water, thus obviating the tendency to foam experienced in all rapid-steaming boilers. If the Water should fall below the tops of the tubes, experience has demonstrated beyond a doubt that long before the crown-sheet would become exposed the tubes would expand suiiiciently to loosen in the heads, thereby forming a safety-valve, as it were, and effectiially preventing a dangerous accumulation of pressure; the worst result or eifcet from the above being that the tubes would require re-caulkiug, which, with the facility aiforded by the removable breechings, can be done with the utmost readiness and despatch.

I do not oonne myself to any peculiar style or form of boiler, but WhatvI claim as new, and desire to secure by Letters Patent, is

A boiler having a {ire-place extending over its entire horizontal area, with the exception of a narrow waterspace surrounding it, and a series of tubes, whether one or more, passing horizontally through the water-space above the fire-place, whenthe said ire-space and the said tube or tubes are connected by and communicate through a combustion chamber formed` outside the boiler, having openings, adjustable or otherwise, for the admission of atmospheric air thereto, and an opening or openings passing through the Water-space surrounding the re-place and communicating with the latter, when the Whole is constructed and arranged so as to-operate substantially in the manner described and for the purpose specified. WM. D ANDREWS Witnesses:

ALBERT W. BROWN, ALEX. F. ROBERTS. 

